Ukrainian marines wiped out a Russian mechanised unit during fierce battles in the Kursk region.
Putin has assembled an army of around 60,000 troops – including some 12,000 North Koreans – as he attempts to reclaim territory seized by Kyiv last year.
Zelensky’s troops stunned the Kremlin when they launched a lightning strike across the border in early August, initially seizing approximately 1,250 square kilometres of land.
Ukraine‘s incursion was the first time that a foreign army had invaded Russia since World War II.
In a recent battle, a Javelin team from Ukraine‘s 36th Marine Brigade inflicted heavy losses on a Russian mechanised unit during an assault.
The team destroyed three tanks and four BMD-4 infantry fighting vehicles over two days.
The brigade later published a video of the battle on its social media channel.
In one clip, four Russian armoured vehicles can be seen moving along a country road.
A Ukrainian soldier is then filmed firing a Javelin missile, which hits its target with unerring accuracy.
The armoured vehicle explodes into flames as the incoming munition wipes it out.
A drone then hovers above the destroyed vehicle as it burns and munitions inside explode.
Ukraine says it wants to use the captured territory as a bargaining chip in any future cease-fire talks with Russia.
Although its army has been steadily pushed back, it still retains several hundred square kilometres of Russian territory and is inflicting huge losses on its enemy.
In particular, North Korean troops have sustained massive casualties as they struggle to adapt to the demands of modern-day warfare.
Western officials told the BBC that North Korea’s army had suffered some 4,000 casualties – 1,000 of whom were killed.
“These are barely trained troops led by Russian officers who they don’t understand,” former British Army tank commander Col Hamish de Bretton-Gordon told the broadcaster.
“Quite frankly, they don’t stand a chance. They are being thrown into the meat grinder with little chance of survival.”